An equivalent metal ion in one- and two-metal-ion catalysis.
Nucleotidyl-transfer enzymes, which synthesize, degrade and rearrange DNA and RNA, often depend on metal ions for catalysis. All DNA and RNA polymerases, MutH-like or RNase H-like nucleases and recombinases, and group I introns seem to require two divalent cations to form a complete active site. The two-metal-ion mechanism has been proposed to orient the substrate, facilitate acid-base catalysis and allow catalytic specificity to exceed substrate binding specificity attributable to the stringent metal-ion (Mg2+ in particular) coordination. Not all nucleotidyl-transfer enzymes use two metal ions for catalysis, however. The betabetaalpha-Me and HUH nucleases depend on a single metal ion in the active site for the catalysis. All of these one- and two metal ion-dependent enzymes generate 5'-phosphate and 3'-OH products. Structural and mechanistic comparisons show that these seemingly unrelated nucleotidyl-transferases share a functionally equivalent metal ion.
Yang
Wei
W
Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, 9000 Rockville Pike, Building 5, Room B1-03 Bethesda, Maryland 20892, USA. Wei.Yang@nih.gov
D002384:Catalysis; D020134:Catalytic Domain; D002413:Cations, Divalent / Q000737:chemistry*; D004265:DNA Helicases / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D008670:Metals / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D009713:Nucleotidyltransferases / Q000737:chemistry / Q000378:metabolism; D016914:Ribonuclease H / Q000737:chemistry / Q000378:metabolism
D002413:Cations, Divalent; D029968:Escherichia coli Proteins; D008670:Metals; D009713:Nucleotidyltransferases; D016914:Ribonuclease H; C027093:TraI protein, E coli; D004265:DNA Helicases